Liquid chromatography-mass spectrometry in forensic toxicology

Investigating hydrophobic environment in alkyl-group-functionalized silica particle with various chain lengths using absorption microspectroscopy

A well-known solvatochromic dye, Reichardt's dye (R-dye), was used to evaluate the hydrophobicity of alkyl-group-functionalized silica particles (ASPs) with different chain lengths. The absorption spectra of R-dye were measured in a single ASP in a mixed solution of water and an organic solvent (methanol (MeOH), ethanol (EtOH), acetonitrile (ACN), tetrahydrofuran (THF), or N,N-dimethylformamide (DMF)) using absorption microspectroscopy. The polarity parameter in the ASPs (ET), determined by the absorption maximum, was observed to be smaller than those in bulk solutions, indicating that R-dye was present in a more hydrophobic environment. In EtOH, THF, and DMF, R-dye was distributed within the alkyl chain layer including the organic solvent. An increase in the organic solvent content of the bulk solution led to a higher organic solvent concentration in the alkyl chain layer, resulting in a decrease in ET. In MeOH and ACN, the R-dye was distributed within the alkyl chain layer and concentrated phase. Moreover, with the increase in the organic molecule content, the distribution of R-dye in the concentrated phase became dominant in MeOH and ACN system, leading to an increase in the ET value. The findings presented in this paper are expected to attract the attention of a wide range of researchers in chromatography.

Follicular Fluid: A Powerful Tool for the Understanding and Diagnosis of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) represents one of the leading causes of anovulatory infertility and affects 5% to 20% of women worldwide. Until today, both the subsequent etiology and pathophysiology of PCOS remain unclear, and patients with PCOS that undergo assisted reproductive techniques (ART) might present a poor to exaggerated response, low oocyte quality, ovarian hyperstimulation syndrome, as well as changes in the follicular fluid metabolites pattern. These abnormalities originate a decrease of Metaphase II (MII) oocytes and decreased rates for fertilization, cleavage, implantation, blastocyst conversion, poor egg to follicle ratio, and increased miscarriages. Focus on obtaining high-quality embryos has been taken into more consideration over the years. Nowadays, the use of metabolomic analysis in the quantification of proteins and peptides in biological matrices might predict, with more accuracy, the success in assisted reproductive technology. In this article, we review the use of human follicular fluid as the matrix in metabolomic analysis for diagnostic and ART predictor of success for PCOS patients.

Direct and rapid characterization of illicit drugs in adulterated samples using thermal desorption electrospray ionization mass spectrometry

Foods and drinks have been adulterated with illicit drugs to facilitate criminal activities. Unfortunately, conventional analytical methods are incapable of rapidly characterizing these drugs in samples, as serious interferences from sample matrices must be removed through tedious and time-consuming pretreatment. Ambient ionization mass spectrometry (AMS) generally does not require sample pretreatment and is thus a suitable tool for directly and rapidly detecting illicit drugs in samples in different physical states. In this study, thermal desorption electrospray ionization mass spectrometry (TD-ESI/MS), an AMS technique, was utilized to efficiently characterize illicit drugs spiked in samples including drinks, powders, and jelly candies. To perform sensitive analysis, the mass analyzer was operated in multiple reaction monitoring mode to monitor the molecular and fragment ions of the target analytes. The time required to complete a typical TD-ESI/MS analysis was less than 30 s. The limits of detection (LODs) for illicit drugs were found to be 100 ppb in drinks, 100–1000 ppb in instant powders, and 1.3–6.5 ng/mm² on stamp surfaces. FM2 and nitrazepam laced in the inner layer of a jelly candy were detected by TD-ESI/MS, showcasing the advantage of the technique for direct and rapid analysis as opposed to conventional methods.

Mass Spectrometry Approaches for Identification and Quantitation of Therapeutic Monoclonal Antibodies in the Clinical Laboratory

Therapeutic monoclonal antibodies (MAbs) are an important class of drugs used to treat diseases ranging from autoimmune disorders to B cell lymphomas to other rare conditions thought to be untreatable in the past. Many advances have been made in the characterization of immunoglobulins as a result of pharmaceutical companies investing in technologies that allow them to better understand MAbs during the development phase. Mass spectrometry is one of the new advancements utilized extensively by pharma to analyze MAbs and is now beginning to be applied in the clinical laboratory setting. The rise in the use of therapeutic MAbs has opened up new challenges for the development of assays for monitoring this class of drugs. MAbs are larger and more complex than typical small-molecule therapeutic drugs routinely analyzed by mass spectrometry. In addition, they must be quantified in samples that contain endogenous immunoglobulins with nearly identical structures. In contrast to an enzyme-linked immunosorbent assay (ELISA) for quantifying MAbs, mass spectrometry-based assays do not rely on MAb-specific reagents such as recombinant antigens and/or anti-idiotypic antibodies, and time for development is usually shorter. Furthermore, using molecular mass as a measurement tool provides increased specificity since it is a first-order principle unique to each MAb. This enables rapid quantification of MAbs and multiplexing. This review describes how mass spectrometry can become an important tool for clinical chemists and especially immunologists, who are starting to develop assays for MAbs in the clinical laboratory and are considering mass spectrometry as a versatile platform for the task.

Surface-enhanced Raman spectroscopy and microfluidic platforms: challenges, solutions and potential applications

The review provides an overview of the development in the field of surface-enhanced Raman spectroscopy combined with microfluidic platforms.

A comprehensive LC/MS analysis of novel cyclopentenedione library

Cyclopentenediones (CPDs) are compounds with a variety of applications ranging from the preparation of functional polymers to the development of antimicrobial agents, suggesting the potential use of CPDs as novel bioactive compounds or drugs. For this reason, a detailed characterization of CPDs and the development of robust analytical methods for their trace analysis are being sought. Here we focused on the design and synthesis of a library of novelized benzylidene CPD derivatives that were consequently characterized by ultra-high performance liquid chromatography (UHPLC) on-line connected with tandem mass spectrometry (MS/MS). The library design was based on a 2-benzylidene-4-cyclopentene-1,3-dione skeleton substituted with a variety of hydroxy, methoxy, halogen, linear aliphatic, heterocyclic and saccharide moieties, primarily modulating the skeleton's hydrophobicity. The prepared CPDs were effectively ionized by positive/negative atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI). After careful optimization of the dopant composition and flow rate, positive-mode APPI proved to be more sensitive than APCI. In negative mode, both ionization techniques gave similar results. Further, a detailed MS fragmentation study was performed, confirming the structure of the compounds and enabling positional isomers of CPDs to be differentiated on the basis of their collision spectra analysis. Finally, an optimization of the composition of the mobile phase and reversed-phased separation mode were done, followed by a selection of the most suitable UHPLC stationary phases, i.e. C18, C8 and phenyl. The applicability of the method was evaluated by the inclusion of the other two substances in the study, i.e. monomeric and dimeric bioactive CPDs, compound TX-1123 and nostotrebin 6 with cytostatic and antimicrobial activities, respectively. The results presented here could be used in further investigations of the chromatographic retention and MS behavior of CPDs, which could be utilized for their isolation, detailed characterization and analysis in biological systems.

Fragmentation of toxicologically relevant drugs in positive-ion liquid chromatography-tandem mass spectrometry

The identification of drugs and related compounds by LC-MS-MS is an important analytical challenge in several application areas, including clinical and forensic toxicology, doping control analysis, and environmental analysis. Although target-compound based analytical strategies are most frequently applied, at some point the information content of the MS-MS spectra becomes relevant. In this article, the positive-ion MS-MS spectra of a wide variety of drugs and related substances are discussed. Starting point was an MS-MS mass spectral library of toxicologically relevant compounds, available on the internet. The positive-ion MS-MS spectra of ∼570 compounds were interpreted by chemical and therapeutic class, thus involving a wide variety of drug compound classes, such benzodiazepines, beta-blockers, angiotensin-converting enzyme inhibitors, phenothiazines, dihydropyridine calcium channel blockers, diuretics, local anesthetics, vasodilators, as well as various subclasses of anti-diabetic, antidepressant, analgesic, and antihistaminic drugs. In addition, the scientific literature was searched for available MS-MS data of these compound classes and the interpretation thereof. The results of this elaborate study are presented in this article. For each individual compound class, the emphasis is on class-specific fragmentation, as discussing fragmentation of all individual compounds would take far too much space. The recognition of class-specific fragmentation may be quite informative in determining the compound class of a specific unknown, which may further help in the identification. In addition, knowledge on (class-specific) fragmentation may further help in the optimization of the selectivity in targeted analytical approaches of compounds of one particular class.

Benzodiazepines: sample preparation and HPLC methods for their determination in biological samples

Benzodiazepines (BDZs) belong to a group of substances known for their sedative, antidepressive, muscle relaxant, tranquilizer, hypnotic and anticonvulsant properties. Their determination in biological fluids is essential in clinical assays as well as in forensics and toxicological studies. Researchers focus on the development of rapid, accurate, precise and sensitive methods for the determination of BDZs and their metabolites. A large number of analytical methods using different techniques have been reported, but none can be considered as the method of choice. BDZs are usually present at trace levels (microgram or nanogram per milliliter) in a complex biological matrix and the potentially interfering compounds must be isolated by various extraction techniques before analysis. An extended and comprehensive review is presented herein, focusing on sample preparation (pretreatment and extraction) and HPLC conditions applied by different authors. These methods enable bioanalysts to achieve detection limits down to 1-2 ng/ml using UV/diode array detection, readily available in most laboratories, and better than 1 ng/ml using electron capture detection, which is lower than that obtained using a nitrogen phosphorus detector. MS interfaced with electrospray ionization offered a similar sensitivity, while negative chemical ionization MS or sonic spray ionization MS provided sensitivity down to 0.1 ng/ml.

Drug-facilitated crimes: definitions, prevalence, difficulties and recommendations. A review

Drug-facilitated crimes are not a new phenomenon but rather an age-old practice. However, reports of drug-facilitated crimes have significantly increased since the mid-1990s. Victims of these crimes or offences report that they were robbed or assaulted while incapacitated by a drug. Most often, these cases have involved strong central nervous system depressant drugs, which have the capability of preventing individuals from consenting to the action of the perpetrator of fighting off their attackers. For all intents and purposes, the drug acts as the offender's weapon, therefore many jurisdictions require analytical proof of its presence, which helps substantiate the alleged victim's claim. This review was undertaken to identify the evolutionary process in the current understanding of allegations of these crimes or offences, so that whoever works in this field may gain a better understanding of the complexities involved in such cases. This review provides several definitions of drug-facilitated crimes, their prevalence in European and English-speaking countries, a list of intoxicating substances, which have so far been incriminated or been suspected to be involved in these crimes or offences, some of the more common difficulties encountered in the investigation, and recommendations to improve detection of the drugs through toxicological analyses.

Thermal desorption counter-flow introduction atmospheric pressure chemical ionization for direct mass spectrometry of ecstasy tablets

A novel approach to the analysis of ecstasy tablets by direct mass spectrometry coupled with thermal desorption (TD) and counter-flow introduction atmospheric pressure chemical ionization (CFI-APCI) is described. Analytes were thermally desorbed with a metal block heater and introduced to a CFI-APCI source with ambient air by a diaphragm pump. Water in the air was sufficient to act as the reactive reagent responsible for the generation of ions in the positive corona discharge. TD-CFI-APCI required neither a nebulizing gas nor solvent flow and the accompanying laborious optimizations. Ions generated were sent in the direction opposite to the air flow by an electric field and introduced into an ion trap mass spectrometer. The major ions corresponding to the protonated molecules ([M + H](+)) were observed with several fragment ions in full scan mass spectrometry (MS) mode. Collision-induced dissociation of protonated molecules gave characteristic product-ion mass spectra and provided identification of the analytes within 5 s. The method required neither sample pretreatment nor a chromatographic separation step. The effectiveness of the combination of TD and CFI-APCI was demonstrated by application to the direct mass spectrometric analysis of ecstasy tablets and legal pharmaceutical products.

Pitfalls and Prevention Strategies for Liquid Chromatography-Tandem Mass Spectrometry in the Selected Reaction– Monitoring Mode for Drug Analysis

Background: We observed cases of false-positive results with the use of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Different LC-MS/MS techniques that use the selected reaction-monitoring mode, routinely employed for the analysis and quantification of drugs and toxic compounds in biological matrices, were involved in the false-positive and potentially false-positive results obtained. We sought to analyze the causes of and solutions to this problem.

Methods: We used a previously reported LC-MS/MS general unknown screening method, as well as manual spectral investigation in 1 case, to perform verification and identification of interfering compounds.

Results: We observed that false-positive results involved: a metabolite of zolpidem that might have been mistaken for lysergic acid diethylamide, benzoylecgonine mistaken for atropine, and clomipramine and 3 phenothiazines that share several common ion transitions.

Conclusions: To prevent problems such as those we experienced, we recommend the use of stable-isotope internal standards when possible, relative retention times, 2 transitions or more per compound when possible, and acceptable relative abundance ratios between transitions, with an experience-based tolerance of ±15% for transitions with a relative abundance >10% and with an extension to ±25% for transitions <10% when the concentration is at the limit of quantification. A powerful general unknown screening procedure can help to confirm suspected interferences. Our results indicate that the specificity of screening procedures is questionable for LC-MS/MS analyses performed in the selected reaction-monitoring mode and involving a large number of compounds with only 1 transition per compound.

Mass spectrometric analysis of illicit drugs in wastewater and surface water

Residues of illicit drugs have been recently found in urban wastewater and surface water. Their levels reflect the amount of drugs collectively excreted by consumers and can therefore be used to estimate drug abuse. An overview of the most widely used illicit drugs and of the analytical methods used for their detection in wastewater and surface water is presented here. Solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry are the techniques that have been used for these investigations. Instrumental conditions and fragmentation patterns of illicit drugs and their metabolites are described.

Simultaneous quantitative determination of amphetamines, ketamine, opiates and metabolites in human hair by gas chromatography/mass spectrometry

A gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the determination of common drugs of abuse in Asia. The method was able to simultaneously quantify amphetamines (amphetamine; AP, methamphetamine; MA, methylenedioxy amphetamine; MDA, methylenedioxymeth mphetamine; MDMA, methylenedioxy ethylamphetamine; MDEA), ketamine (ketamine; K, norketamine; NK), and opiates (morphine; MOR, codeine; COD, 6-acetylmorphine; 6-AM) in human hair. Hair samples (25 mg) were washed, cut, and incubated overnight at 25 degrees C in methanol/trifluoroacetic acid (methanol/TFA). The samples were extracted by solid-phase extraction (SPE), derivatized using heptafluorobutyric acid anhydride (HFBA) at 70 degrees C for 30 min, and the derivatives were analyzed by electron ionization (EI) GC/MS in selected ion monitoring mode. Confirmation was accomplished by comparing retention times and the relative abundances of selected ions with those of standards. Deuterated analogs of the analytes were used as internal standards for quantification. Calibration curves for ten analytes were established in the concentration range 0.1-10 ng/mg with high correlation coefficients (r2 > 0.999). The intra-day and inter-day precisions were within 12.1% and 15.8%, respectively. The intra-day and inter-day accuracies were between -8.7% and 10.7%, and between -5.9% and 13.8%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) obtained were 0.03 and 0.05 ng/mg for AP, MA, MDA, MDMA and MDEA; 0.05 and 0.08 ng/mg for K, NK, MOR and COD; and 0.08 and 0.1 ng/mg for 6-AM. The recoveries were above 88.6% for all the compounds, except K and NK which were in the range of 71.7-72.7%. Eight hair samples from known polydrug abusers were examined by this method. These results show that the method is suitable for broad-spectrum drug testing in a single hair specimen.

The pharmacology of lysergic acid diethylamide: a review

Lysergic acid diethylamide (LSD) was synthesized in 1938 and its psychoactive effects discovered in 1943. It was used during the 1950s and 1960s as an experimental drug in psychiatric research for producing so-called "experimental psychosis" by altering neurotransmitter system and in psychotherapeutic procedures ("psycholytic" and "psychedelic" therapy). From the mid 1960s, it became an illegal drug of abuse with widespread use that continues today. With the entry of new methods of research and better study oversight, scientific interest in LSD has resumed for brain research and experimental treatments. Due to the lack of any comprehensive review since the 1950s and the widely dispersed experimental literature, the present review focuses on all aspects of the pharmacology and psychopharmacology of LSD. A thorough search of the experimental literature regarding the pharmacology of LSD was performed and the extracted results are given in this review. (Psycho-) pharmacological research on LSD was extensive and produced nearly 10,000 scientific papers. The pharmacology of LSD is complex and its mechanisms of action are still not completely understood. LSD is physiologically well tolerated and psychological reactions can be controlled in a medically supervised setting, but complications may easily result from uncontrolled use by layman. Actually there is new interest in LSD as an experimental tool for elucidating neural mechanisms of (states of) consciousness and there are recently discovered treatment options with LSD in cluster headache and with the terminally ill.

Determination of bromadiolone in whole blood by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A rapid, sensitive and selective high-performance liquid chromatography tandem mass spectrometric method (HPLC/MS-MS) has been developed and validated for the determination of bromadiolone in whole blood using warfarin as an internal standard (IS). Bromadiolone was extracted from the whole blood samples by liquid-liquid extraction with ethyl acetate. Multiple-reaction monitoring (MRM) was used to detect bromadiolone and IS, using precursor --> product ion combinations at m/z 527 --> 465 and 307 --> 161, respectively. The calibration curve was linear (r2=0.998) in the concentration range of 0.5-100.0 ng/mL with a lower limit of quantification of 0.5 ng/mL in whole blood. Intra- and inter-day relative standard deviations (R.S.D.s) were less than 7.5 and 11.9%, respectively. Recoveries of bromadiolone ranged from 82.1 to 85.2%. This method is found to be determined trace bromadiolone in whole blood and can be used in the diagnosis of the poisoned human beings.

Broad-spectrum toxicological analysis of hair based on capillary zone electrophoresis–time-of-flight mass spectrometry

The coupling of capillary electrophoresis-electrospray ionization and time-of-flight mass spectrometry, combining efficiency and speed of separation with high mass accuracy and fast scanning capability, was for the first time applied to the determination of drugs of abuse (amphetamine, methamphetamine, MDA, MDMA, ephedrine, cocaine, morphine, codeine) and their metabolites in hair (6-MAM, benzoylecgonine). Experimental conditions were as follows. Separation: voltage 15 kV, uncoated fused-silica capillary (75 microm ID, 100 cm total length), running electrolyte 25 mM ammonium formate, pH 9.5, field-amplified sample stacking injection. Forensic drugs could be identified by exact mass determination (mass accuracy typically < or = 5 ppm) and by match of the isotopic pattern. The method was fully validated, showing limit of detections (LODs) suitable for the determination of all the compounds below the cut-off usually adopted for hair analysis (0.1 ng/mg). Analytical precision in real matrices (tested at 0.1 and 1.0 ng/mg) was typically characterized by CV's < or = 24% in both intra-day and day-to-day experiments. Quantitative determination was also tested by using a single internal standard (folcodine). Results, although with a moderate accuracy, conceivably depending on the lack of deuterated internal standards, proved useful for diagnostic use of the results from hair analysis. A single liquid-liquid extraction procedure was applied for all analytes, allowing the detection of a broad spectrum of basic drugs and their major metabolites.

Quantitative analysis of cocaine and its metabolites in whole blood and urine by high-performance liquid chromatography coupled with tandem mass spectrometry

AIM

In forensic toxicology it is important to have specific and sensitive analysis for quantification of illicit drugs in biological matrices. This paper describes a quantitative method for determination of cocaine and its major metabolites (ecgonine methyl ester, benzoylecgonine, norcocaine and ethylene cocaine) in whole blood and urine by liquid chromatography coupled with tandem mass spectrometry LC/MS/MS.

METHOD

The sample pre-treatment (0.20 g) consisted of acid precipitation, followed by centrifugation and solid phase extraction of supernatant using mixed mode sorbent columns (SPEC MP1 Ansys Diag. Inc.). Chromatographic separation was performed at 30 degrees C on a reverse phase Zorbax C18 column with a gradient system consisting of formic acid, water and acetonitrile. The analysis was performed by positive electrospray ionisation with a triple quadropole mass spectrometer operating in multiple reaction monitoring (MRM) mode. Two MRM transitions of each analyte were established and identification criteria were set up based on the retention time and the ion ratio. The quantification was performed using deuterated internal analytes of cocaine, benzoylecgonine and ecgonine methyl ester. The calibration curves of extracted standards were linear over a working range of 0.001-2.00 mg/kg whole blood for all analytes. The limit of quantification was 0.008 mg/kg; the interday precision (measured by relative standard deviation-%RSD) was less than 10% and the accuracy (BIAS) less than 12% for all analytes in whole blood. Urine samples were estimated semi-quantitatively at a cut-off level of 0.15 mg/kg with an interday precision of 15%.

CONCLUSION

A liquid chromatography mass spectrometric (LC/MS/MS) method has been developed for confirmation and quantification of cocaine and its metabolites (ecgonine methyl ester, benzoylecgonine, norcocaine and ethylene cocaine) in whole blood and semi-quantitative in urine. The method is specific and sensitive and offers thereby an excellent alternative to other methods such as GC-MS that involves derivatisation.

Ultraperformance Liquid Chromatography−Tandem Mass Spectrometry Analysis of Stimulatory Drugs of Abuse in Wastewater and Surface Waters

Ultraperformance liquid chromatography coupled to electrospray tandem mass spectrometry was used for the rapid and simultaneous analysis of 15 stimulatory drugs in water. Cocaine, amphetamine-related compounds, LSD, ketamine, PCP, fentanyl, and metabolites, among the controlled drugs, and nicotine, caffeine, and their metabolites, among the noncontrolled drugs, were studied. Chromatographic separation was achieved in less than 4.5 min, with improved peak resolution and sensitivity. Identification and quantification of the compounds of interest was performed by selected reaction monitoring, using an electrospray ionization source. Isotope dilution (except for paraxanthine) was used for quantitation. Quality parameters of the method were established, and limits of quantification were obtained for controlled drugs in surface waters from 0.1 to 3.1 ng/L and in wastewaters from 0.2 to 4.0 ng/L. Run-to-run and day-to-day precisions were evaluated in different water matrixes (Milli-Q water, surface water, wastewater). To assess the presence of these drugs in real water samples, the optimized method was applied to the analysis of wastewater and surface river water. The analysis of several samples from wastewater treatment plants in northeast Spain revealed the presence of drugs such as cocaine and amphetamine-related compounds, in both influent and effluent samples. Cocaine metabolite and MDMA (ecstasy) were also found in surface waters while nicotine and caffeine were detected in all the analyzed samples. The results obtained demonstrate that the presence of these drugs in the aquatic media must be considered a matter of environmental concern.

Current role of liquid chromatography–mass spectrometry in clinical and forensic toxicology

This paper reviews multi-analyte single-stage and tandem liquid chromatography-mass spectrometry (LC-MS) procedures using different mass analyzers (quadrupole, ion trap, time-of-flight) for screening, identification, and/or quantification of drugs, poisons, and/or their metabolites in blood, plasma, serum, or urine published after 2004. Basic information about the biosample assayed, work-up, LC column, mobile phase, ionization type, mass spectral detection mode, and validation data of each procedure is summarized in tables. The following analytes are covered: drugs of abuse, analgesics, opioids, sedative-hypnotics, benzodiazepines, antidepressants including selective-serotonin reuptake inhibitors (SSRIs), herbal phenalkylamines (ephedrines), oral antidiabetics, antiarrhythmics and other cardiovascular drugs, antiretroviral drugs, toxic alkaloids, quaternary ammonium drugs and herbicides, and dialkylphosphate pesticides. The pros and cons of the reviewed procedures are critically discussed, particularly, the need for studies on matrix effects, selectivity, analyte stability, and the use of stable-isotope labeled internal standards instead of unlabeled therapeutic drugs. In conclusion, LC-MS will probably become a gold standard for detection of very low concentrations particularly in alternative matrices and for quantification in clinical and forensic toxicology. However, some drawbacks still need to be addressed and finally overcome.

Fischer Carbene Complexes: Beautiful Playgrounds To Study Single Electron Transfer (SET) Reactions

The knowledge of the reactivity of Fischer carbene complexes in electron transfer processes is still in the early stage of development, but interesting advances are foreseeable in this young branch of metal-carbene chemistry. Although these compounds have a dual reactivity (which makes them good substrates for oxidation and reduction processes), their behavior towards chemical electron transfer (ET) reagents was unknown until very recently. This article covers the progress accomplished in the reactivity of these compounds towards chemical ET reagents (C(8)K or SmI(2)), as well as the use of nonconventional sources of electrons, such as electrospray ionization (ESI) to induce ET processes. Special emphasis will be made on the effect of the structure of the starting carbene in the outcome of the reaction and in discussing the different mechanisms proposed.

Determination of drugs of abuse and their metabolites in human plasma by liquid chromatography–mass spectrometry

A method, using 0.2 ml of plasma, was designed for the simultaneous determination of morphine, 6-monoacetylmorphine, amphetamine, methamphetamine, MDA, MDMA, MDEA, MBDB, benzoylecgonine and cocaine. The drugs were analysed by LC-MS, after solid phase extraction in the presence of the deuterated analogues. Reversed phase separation on an Atlantis dC18 column was achieved in 10 min, under gradient conditions. The method was full validated, including linearity (2-250 ng/ml, r2>0.99), recovery (>50%), within-day and between-day precision and accuracy (CV and bias <15%), limit of detection (0.5 and 1 ng/ml) and quantitation (2 ng/ml), relative ion intensities and no matrix effect was observed. The procedure showed to be sensitive and specific, and was applied to 156 real cases from road fatalities (7.1% cases positive to cocaine and 0.6% to designer drugs).

Enhanced mass resolution method development, validation and assay application to support preclinical studies of a new drug candidate

A very highly sensitive and highly selective liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed to evaluate and quantify a new drug candidate in different biological matrices. Following a simple plasma protein precipitation using acetonitrile, the post-treatment samples were analyzed on a C18 column interfaced with a new generation of triple-quadrupole mass spectrometer. The recently introduced triple-quadrupole mass spectrometer, the TSQ Quantum Ultra, with enhanced mass-resolution capability, demonstrated improved sensitivity (0.05 ng/mL), coupled with suitable accuracy and precision, over a broad linear dynamic range (0.05-1000 ng/mL). A comparison of the assay performance data (dynamic range, calibration curve equation, precision and accuracy) of the enhanced resolution method against a unit resolution method under optimized conditions showed the performance improvement of the enhanced mass resolution method for bioanalytical high-throughput applications. The enhanced mass resolution method herein described was successfully applied to the evaluation of the pharmacokinetic profile of a new drug candidate in rat, rabbit and dog plasma samples.

Surface-activated chemical ionization ion trap mass spectrometry in the analysis of drugs in dilute urine samples. Part II: analysis of morphine and other street drugs

The new ionization method, called surface-activated chemical ionization (SACI), was employed for the analysis of fives drugs (morphine, codeine, 6-monoacetylmorphine (6-MAM), benzoylecgonine and cocaine) by ion trap mass spectrometry. The results so obtained have been compared with those achieved by using atmospheric pressure chemical ionization (APCI), no-discharge-APCI and electrospray ionization (ESI) clearly showing that SACI is the most sensible one mainly due to the high ionization efficiency and the lower chemical noise. The performance of SACI in terms of sensitivity and linearity was compared with the sensitivity and linearity obtained using APCI, no-discharge-APCI and ESI, showing that the new SACI approach gives rise to the best results. Then, SACI was used to analyze morphine, codeine, 6-MAM, benzoylecgonine and cocaine in urine samples. After the optimization of the instrumental parameters for a mixture of the standard compounds, eight urine samples were analyzed. They were strongly diluted (1 : 20 and 1 : 100) in order to prevent the chromatographic column damage due to the matrix composition. Furthermore, the diluted urine samples were directly analyzed, without pretreatment, through LC-MS and LC-MS/MS, and the obtained results are reported.

Liquid chromatography–electrospray ionisation mass spectrometry for the determination of nine selected benzodiazepines in human plasma and oral fluid

A new simple and rapid liquid chromatographic-mass spectrometric technique was designed for the determination of nine benzodiazepines in plasma and oral fluid. Benzodiazepines were extracted from alkalinised spiked and clinical plasma and oral fluid samples using a single step, liquid-liquid extraction procedure with diethyl ether. The chromatographic separation was performed with a Xterra RP18, 5 microm (150 x 2.1 mm i.d.) reversed-phase column using deuterated analogues of the analytes as internal standard. The recovery ranged from 70.3 to 86.9% for plasma and 63.9 to 77.2% for oral fluid. The limits of detection ranged from 0.5 to 1 ng/ml in plasma and 0.1 to 0.2 ng/ml for oral fluid. The method was validated for all the compounds, including linearity and the main precision parameters. The procedure, showed to be sensitive and specific, was applied to real plasma and oral fluid samples. The method is especially useful to analyse saliva samples from drivers undergoing roadside drug controls.